Due to their high performance, automotive style brazed heat exchangers are being developed for residential air conditioning applications. An example of such a heat exchanger is disclosed in US Patent Application Publication 2009/0173483 by Beamer et al., published Jul. 9, 2009. As shown in FIG. 1, automotive style heat exchangers typically have a pair of headers 22, 24 with a plurality of refrigerant tubes 26 defining fluid passages 28 to provide fluidic communication between the headers 22, 24. The refrigerant tubes 26 extend in a spaced and parallel relationship and are generally perpendicular to the header axes 23 and 25. A pair of core supports 30 are disposed outwards of the refrigerant tubes 26 and extend between the headers 22, 24 in a parallel and spaced relationship to the refrigerant tubes 26. The core supports 30 add structural support to the heat exchanger assembly 20 and protect a plurality of cooling fins 32. The plurality of cooling fins 32 are disposed between adjacent refrigerant tubes 26 and between each core support 30 and the next adjacent of the refrigerant tubes 26 for transferring heat from the refrigerant tubes 26. The plurality of refrigerant tubes 26 and plurality of cooling fins 32 define a heat exchanger core 34.
FIG. 1 illustrates a heat exchanger assembly 20 wherein a refrigerant conduit 36 enters the heat exchanger assembly 20 axially through a header end cap 38. A connector tube 40 is attached to and is in fluidic communication with the refrigerant conduit 36. In heat exchanger assemblies that require the axis of the connector tube to be perpendicular to the header axis 23, the connector tube 40 includes a perpendicular bend external to the header. The refrigerant conduit 36 and connector tube 40 as shown in FIG. 1 may be installed in the inlet header 22. Alternatively the refrigerant conduit 36 and connector tube 40 may be installed the outlet header 24 or both the inlet and the outlet header 22, 24. Those skilled in the art understand that the bend radius of the inlet connector tube 40 is generally limited by the diameter of the tube, the material of the tube and the smoothness inside the connector tube 40 needed to minimize refrigerant pressure difference. As such, the bend radius of the connector tube 40 is often a limiting factor in minimizing the effective length of the connector tube 40 along the header axis 23 or 25 which undesirably affects the length of the inlet and outlet headers 22, 24 as shown below.
In a typical residential air conditioning system, the heat exchanger assembly 20 is positioned in an air duct to direct air flow through the heat exchanger core 34. The length of the headers 22, 24 plus the effective length of the connector tube 40 along the header axis 23 or 25 determines the heat exchanger assembly's packaging width 46, see FIG. 1. The packaging width 46 is limited by the air conditioning system's cabinet width.
Because of the connector tube radius, the length of the headers 22, 24 is limited in order to meet a predetermined packaging width 46. The reduced header length likewise reduces the heat exchanger core width 48, thus reducing the area of the heat exchanger core 34. It would be recognized by those skilled in the art that reducing the heat exchanger core area diminishes heat exchanger assembly performance by reducing the heat capacity of the heat exchanger assembly and increasing the air pressure difference of air flowing through the heat exchanger assembly. Reducing the heat exchanger core width 48 typically requires reducing the number of refrigerant tubes 26 in the heat exchanger core 34. This increases a refrigerant pressure difference between the inlet header 22 and outlet header 24, which is also usually detrimental to heat exchanger performance. Additionally, a blocking baffle 42 may be required within the air duct to prevent air flow directed to the heat exchanger core 34 from bypassing the heat exchanger core 34 and flow through an open area defined by connector tube 40. Therefore, it would be desirable to maximize the heat exchanger core width 48 and minimize the effective length of the connector tube 40.
As disclosed by Beamer, automotive style heat exchangers adapted for residential air conditioning and heat pump applications typically have longer headers 22, 24 than automotive heat exchangers. The increased length has made it more difficult to insert a refrigerant conduit 36 into the header 22, 24 during the manufacturing process. The refrigerant conduit 36 must be properly aligned to prevent damage to the refrigerant conduit 36 or the refrigerant tubes 26. This requires great care on the part of the manufacturing operator or special fixtures to assure proper alignment.
Accordingly, there remains a need for a heat exchanger that is easy to manufacture and provides optimized heat exchanger core area and refrigerant distribution.